All Questions
Tagged with terminology units
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Absorption and emission spectrum terminology
Hi everyone recently i was looking for laser crystals and since I am an autodidact i was confused by the terminology and units of the optics domain. And specialy by the absorption and emission ...
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Why is the term 'Accuracy of 1 part in $x$' used?
My question stems from how we measure the accuracy of Caesium clocks. Most Caesium clocks are said to have an accuracy of '$1$ part in $10^{14}$.'
I understand that the terminology means to convey ...
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2
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Unit in unit area
Pressure is defined as force per unit area. What is the meaning of unit and why is the term unit used with area?
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Per unit quantity meaning
What does per unit quantity mean? like distance covered per unit time? Or mass per unit volume?
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Why is excitation potential taken in $\rm eV$ when $\rm eV$ is actually the unit of energy and not potential difference? Shouldn’t it be Volt?
The unit of excitation potential should be Volt and not $\rm eV$. My book says it’s $\rm eV$.
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What do you call the power of a unit of measure?
Regarding units of measurement, it's possible to have powers (e.g. the meter, the square meter, the cubic meter). Is this called the “power” of the unit? Order? Dimension ("dimension" is ...
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Name for the inverse of the heating/cooling rate?
I would call the average change in temperature of a body per unit time "cooling rate" or "heating rate" depending on the sign. Is there a name for the inverse of this quantity, i.e....
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Why are people using 'lightyear' as a measurement of time? [closed]
I came across 2 people in an open forum, who are college students, who that agree using the term 'lightyear' as a measurement of time is correct. Their context was "This country's technology is ...
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4
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Why do we say "pound feet of torque" when stating torque?
This is kind of a grammar question, but when stating a measurement, like distance, force, time, or volume, we generally say 5 gallons, 50 lbs, or 10 miles etc. It is understood we are talking about ...
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What does a.u. mean as unit (not astronomical unit) in graphs in physics publications?
For example, in this paper (also arXiv), it uses a.u. as the unit in multiple graphs for the quantiy $\frac{dI}{dV}$, for example in Figure 3. I am suspecting a.u. means "appropriate unit," ...
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What is the constant in $F=kma$ called?
I understand fully where the constant comes from and why it is defined as $k=1\ \text{N}\ \text{kg}^{-1}\ \text{m}^{-1}\ \text{s}^2$
But does it have an official name?
If I were to give it a name I ...
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Question about Schrodinger equation in atomic units vs in SI units
In SI units, we see that the Schrodinger equation can be written as
\begin{align}
i\hbar\partial_t \Psi= \left(-\frac{\hbar^2}{2m_e}\Delta_x+V(x)\right)\Psi
\end{align}
whereas, in atomic units, we ...
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What is the difference between degree celsius and celsius degree? [duplicate]
It seems similar but can you guys please answer it that what is a specific difference between degree celsius and celsius degree?
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Confusion on Centigrade/Celsius Scale
There came the centigrade scale. The issue was that many solid/liquid thermometric substances didn't respond to temperature linearly so different thermometers produced different results. This was ...
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Name of measurement expressed as the sum of different units
In a paper I'm writing, I want to make a comment about errors in an old paper made when doing arithmetic with measurements expressed as as the sum of quantities with two or more different units, for ...
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